1. Field
The technology described herein relates to complementary metal oxide semiconductor (CMOS) transducers and methods for forming the same.
2. Related Art
Capacitive Micromachined Ultrasonic Transducers (CMUTs) are known devices that include a membrane above a micromachined cavity. The membrane may be used to transduce an acoustic signal into an electric signal, or vice versa. Thus, CMUTs can operate as ultrasonic transducers.
Two types of processes can be used to fabricate CMUTs. Sacrificial layer processes form the membrane of the CMUT on a first substrate above a sacrificial layer. Removal of the sacrificial layer leaves behind the membrane above a cavity. Wafer bonding processes bond two wafers together to form a cavity with a membrane.